Northern Hemisphere sea ice variability in a transient CGCM simulation of the past 2.6 Ma.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39746961.
- Also identified by DOI 10.1038/s41467-024-55327-2 and PMC identifier 11695940.
- Licence recorded as CC BY-NC-ND.
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Abstract
The recent sea ice changes in the Northern Hemisphere (NH), necessitate elucidating the sea ice variability over the past 2.6 million years (Ma), when the Earth's glacial cycles transitioned from ∼41 to ∼100 kyr periodicity, following the Mid-Pleistocene Transition (MPT) period (0.7-1.2 Ma). Here, we analyze a coupled general circulation model (CGCM) simulation to understand how the NH sea ice responds to changes in the transient orbital, greenhouse gas (GHG), and ice-sheet forcings. We find that the Earth's axial tilt (obliquity) and axial wobble (precession) strongly influence the variability in high-latitude (>70° N) perennial sea ice and mid-latitude (35° N-70° N) seasonal sea ice, respectively, by modifying the net surface shortwave radiation. Meanwhile, the GHG forcing affects the glacial-interglacial sea ice predominantly in the Labrador Sea, Irminger-Iceland basin sector, and Central North Pacific regions during the MPT and post-MPT (0.0-0.7 Ma) periods by modulating the downwelling longwave radiation. Additionally, we confirm that variability with longer periodicity (∼100 kyr) from GHG and ice-sheet forcings is most pronounced in NH sea ice during the MPT and post-MPT periods.